Arbitrage

Arbitrage

Strategy

Definition

A strategy that takes advantage of differing odds at two or more outlets to lock in a risk-free profit. By betting on all outcomes with carefully proportioned stakes, an arbitrageur guarantees a positive return no matter who wins. These opportunities (“arbs”) are usually small and fleeting because sportsbooks adjust quickly.

Formula

For two outcomes A and B: an arbitrage exists if $\frac{1}{\text{Decimal Odds}_A} + \frac{1}{\text{Decimal Odds}_B} < 1$. Stake proportion: bet $\frac{\text{Total}}{\text{Decimal Odds}_A}$ on A and $\frac{\text{Total}}{\text{Decimal Odds}_B}$ on B.

Example

One book has Canelo -130 (1.77 decimal) and another has Crawford +150 (2.50 decimal). This is an **arbitrage** spot: $1/1.77 + 1/2.50 ≈ 0.565 + 0.400 = 0.965 < 1$. You could bet \$565 on Canelo at -130 and \$400 on Crawford at +150, for a total outlay of \$965. If Canelo wins, return = \$565×(1.77) = \$1000. If Crawford wins, return = \$400×(2.50) = \$1000. In either case you get \$1000 back on \$965 bet, netting \~\$35 risk-free profit.